• Adventures in menu labeling

    Some of you took umbrage with my saying that I’m skeptical of menu-labeling for obesity prevention. I get your main point – that this shouldn’t be so hard. Yet it is, for many reasons. There’s a new study in JAMA that shows one reason why:

    Context National recommendations for the prevention and treatment of obesity emphasize reducing energy intake. Foods purchased in restaurants provide approximately 35% of the daily energy intake in US individuals but the accuracy of the energy contents listed for these foods is unknown.

    Objective To examine the accuracy of stated energy contents of foods purchased in restaurants.

    Design and Setting A validated bomb calorimetry technique was used to measure dietary energy in food from 42 restaurants, comprising 269 total food items and 242 unique foods. The restaurants and foods were randomly selected from quick-serve and sit-down restaurants in Massachusetts, Arkansas, and Indiana between January and June 2010.

    Main Outcome Measure The difference between restaurant-stated and laboratory-measured energy contents, which were corrected for standard metabolizable energy conversion factors.

    Gotta love studies like these. Researchers went into restaurants with menu-labeling and bought their food. Then they took them to the lab and measured how close the stated caloric content was to the actual caloric content. To be eligible, a restaurant had to be in a chain with sales placing them in the top 400 in 2008, and had to be either “quick-serve” or “sit-down”. They also had to have calorie content reported on their website.

    How accurately did they report the calories in their food items?

    Well, overall, they were pretty accurate. But individual items showed a lot more variation. Of the 269 food items that were measured, almost 20% had 100 or more actual calories than what was stated. The worst offender, a side dish, had more than 1000 calories in a portion that was reported to have only 450 calories.

    Now it’s possible that the researchers got a bad sample. Perhaps their was an overeager server that night who gave them more than they were supposed to get. So, in the interest of accuracy, the researchers took some of the worst offenders, and went back and got a second sample. They were able to do this for 13 of the 17 foods with foods with the largest discrepancies between the reported and measured calories. In the first pass, these food items had 289 more calories on average than reported. In the second look, they still had 258 more calories than reported. Most concerning for those trying to watch what they eat, the food items with lower reported calories (ie healthy or diet items) were significantly more likely to have higher calories than reported. This was balanced, oddly enough, but the high-reported calorie foods having fewer calories than reported.

    Now, this isn’t to say that I think the restaurants were lying. But if you’re a chain, there is bound to be some variation in portion sizes and contents. Calories will vary, sometimes significantly.

    If you want to be positive of something, you have to make it yourself. I still say the secret to weight loss is: eat less, and exercise.

    • “If you want to be positive of something, you have to make it yourself. I still say the secret to weight loss is: eat less, and exercise.”

      Of course if you run a caloric deficit you will lose weight. The point is that it is much easier to run a caloric deficit on some diets than others. If your calories come primarily from wheat and sugar, you will find it very difficult to run a caloric deficit – you’ll feel tired, weak and hungry. If you eat well, you’ll run a caloric deficit much more easily. Read anything Gary Taubes has written in the last ten years.

    • I’m only a sample size of 1, but nutritional labelling has proven very beneficial to me. For my purposes, it’s not necessarily the absolute caloric/fat/sodium content that’s important so much as the comparitive amounts.

      That is to say that in the past when ordering one of my 21 meals/week in a restaurant, I would sometimes choose what I thought were healthy foods. But I was startled to find that often the apparently healthy foods were the worst of the lost. The most glaring example was a chicken ceasar salad at popular, upscale local chain. That “salad” contained more fat, more calories and more sodium then 4.5 BigMacs!

      So it doesn’t matter if every item on the menu us “under reported” by 300 calories, so long as the discrepency is relatively consistent (which of course it might not be.) But if instead of ordering that salad above, I ordered a 6oz sirloin steak, steamed vegies, and a piece of lemon marangue pie, I would be much better off in terms of all three criteria that I use (colories, fat, sodium.)

      Reading the labels on store bought items, using a service offered by the local paper ( http://www.vancouversun.com/life/food/fatabase/index.html ) , and seeking the advice of a registered dietician have allowed me to lose just under a pound a week (my original goal) for about 10 months to date. More importantly even though my BP meds have been reduced from 10mg/day to 5mg/day (Norvasc) my BP has dropped from the range of 150/100 to, at my last GP visit 3 weeks ago to 120/70. These improvements have come about almost exclusively through dietary changes.

      I think the nutrition labelling is, or at least can be, very useful. The real problem is in using it effectively.

    • Losing weight IS hard and that’s why people don’t do it. It’s so much easier (and cheaper but that’s another discussion) to buy prepared foods than to make everything yourself, that we’ve become lazy and complacent. I, too, have been losing weight recently because I was just tired of being overweight and out of shape. Even though I’ve been at it for 4 months (lost 30 pounds so far), it still takes effort on my part every day and almost every meal. That’s hard to keep up.

      But, having calorie counts on menus or available in some form HAS helped me. We don’t go to restaurants that don’t have readily available nutrition information as much as we used to. When we do go to restaurants, I will choose some of the lower calorie items available and I watch how much of everything I eat. Just because they bring it on the plate doesn’t mean you have to eat it. While there may be problems, I think this is a step in the right direction and, given time, will be regulated (whether by gov’t or the people as in your example) into fairly decent compliance.

    • Thanks for writing on this paper. It’s definitely a fun one. Since you were a chem major, Dr. Carroll, I thought you might enjoy thinking through a possible issue regarding the methods of the paper. I’ll try to make it quick.

      As I was walking home eating a slice of pizza tonight, I thought about its energy content, your blog post, and my college chem classes (not a major, though). A bomb calorimeter is meant to measure total combustible energy (i.e. how much energy is released when the food molecules break down, the carbons grab oxygen atoms, and turn into CO2). A food calorie label is meant to measure metabolic energy (the energy you absorb from the food). These two will not be the same (the latter smaller than the former, because of the first law of thermodynamics). The authors of the paper adjust for this discrepancy by taking the stated nutrient content of the food (i.e. protein, fat etc.) and using conversion coefficients to get to the expected combustible calories. However, and here’s my point, this method doesn’t seem to take account of artificial sweeteners that I imagine are not counted among the nutrient content in the labels. These ingredients will carry roughly the same bomb caloric content as normal sugars, but have zero metabolic calories. So, if something’s made with splenda rather than sugar, its actual calorie content will be overestimated in this study. That wouldn’t necessarily affect the variance, but it would affect the mean.

      This isn’t my field, and the authors have seven doctorates among them, but my college chemistry mind is telling me something could be up.